caluculating cumm% in BEX

Defect qty

X 2

Y 4

Z 5

A 3

This data I will have in the cube mow based on this I need to do cummalation on qty value

Like

Defect qty Cumm

X 2 2

Y 4 6

Z 5 11

A 3 14

___ ____

14 14

This cummulation I have done by selecting the option cumulated values

Now I need to calculate cumm%

Defect qty Cumm cumm%

X 2 2 2/14*100

Y 4 6 6/14*100

Z 5 11 11/14*100

A 3 14 14/14*100

I need to calualte the cumm % on overall result of cumm